Vibrating table



June 20, 1950 c. M. G. CALVER 2,512,304

VIBRATING TABLE Filed March 14, 1946 H 5 Sheets-Sheet 1 K M29? 5/wlggw/ffi June 20, 1950 c; M. e. CALVER 2,512,304

VIBRATING TABLE Filed March 14, 1946 5 Sheets-Sheet 2 Wwawvz 6/6/4 W654.11456 SEARCH H t M. G. CALVER VIBRATING TABLE June 20, 1950 5Sheets-Sheet 4 Filed March 14, 1946 Jame 20, E950 c, M. G. CAM/ER sfi yVIBRATING TABLE Filed March 14, 1946 5 sneew-smm 5 Patented June 20,1950 VIBRATING TABLE Cyril Maurice Grahame Calver, Bushey, EnglandApplication March 14, 1946, Serial No. 654,288 In Great Britain March15, 1945 11 Claims.

This invention consists in improvements in or relating to vibratingtables which have been particularly designed for testing aircraftinstruments under conditions which can be adjusted to simulate veryclosely the vibration conditions to which those instruments would besubjected when the aircraft carrying them is in flight. Although theinvention is primarily designed for this purpose it is to be understoodthat it is not limited to this use and may be employed for any purposein which a vibrating table is required to be vibrated in two planesdisposed at an angle to one another, e. g. at a right-angle and in whichthe phase relationship of vibrations can be readily adjusted.

The present invention comprises broadly in combination a vibratorytable, a carriage for the table permitting movement of the latter in twoplanes angularly displaced, at least two rotary shafts having aneccentric coupling to the table with the two shafts disposed with theiraxes angularly displaced with respect to one another at the requiredangle and means to adjust the eccentricity of the coupling between eachshaft and the table.

One preferred example of the invention will now be described with theaid of the accompanying drawings in which:

Figure 1 is a side elevation showing the vibration table together withthe main driving motor, Figure 2 is a section on the 22 of Figure 1,

Figure 3 is a section in a plane at right-angles to that of Figure 2 andcontaining the axis of the main driving shaft.

Figure 4 is a section of a detail taken on the line 4-4 of Figure 3, and

Figure 5 is a diagrammatic illustration of a portion of the vibratoryshaft shown in Figure 2 to i1- lustrate more clearly the eccentricity ofthe shaft and the several parts associated with it.

Figure 6 is an exploded view of the main parts making up the vibratorytable and sub-frame and Figure 7 is an enlarged sectional detail of thecoupling to one of the main vibration shafts and the means for angularlyadjusting it.

Like reference numerals indicate like parts in the several figures ofthe drawings.

The main base I0 upon which the table is supported may be of anypreferred form and is conveniently a metal casting in which are providedbearings II and I2 for main driving shaft I3.

, Driving through a coupling 85 this shaft rotates driving shaft I I3 towhich is splined a bevel gear I4 with which are engaged two other bevelgears I 5 and I6 mounted respectively on two vibration shafts I1 and I8.One of these vibration shafts, namely the shaft I1, is arranged with itsaxis at right-angles to and in a plane containing the axis of the maindriving shaft H3. This shaft as shown in Figure 5, has ground ends I I!which rotate in the shaft bearings, the centre portion I9 iseccentrically ground to ends I IT. This centre portion I9 carries atightly fitting sleeve 20, the outside of which is also ground eccentricwith its own bore and the centre portion I9. The axes for the respectiveparts I1, I!) and 20 are indicated at 2I 22 and 23 respectively. It isto be understood, however, that eccentricity of the various parts isgrossly exaggerated in the illustration in order to show therelationship of these eccentrically designed parts, and in practice, asonly comparatively small vibrations are required the degree ofeccentricity in all cases will be comparatively slight.

Sleeve 20 is in actual construction, as shown in Figure 2, composed ofthree portions, 24, 25 and 26 of which the outer portions 24 and 26 arecarried in bearings indicated as a whole by reference numerals 21 and28. These bearings are carried in housings 29 and 30 provided in thebottom of a sub-frame 3| to which vertical vibrations will be impartedwhen shaft I1 is rotated.

As shown more clearly in Figures 3 and 6, the vibratory table 32 issupported on sub-frame 3| through the medium of a spaced series of balls33 which are housed in a ring 34 so that vertical motion is transmittedfrom the sub-frame to the table through balls 33. At the same time theseballs provide an anti-friction support for table 32 when it is topartake of vibrations, say in the horizontal plane or in any plane inwhich a second series of vibrations is intended.

In the example shown, the two sets of vibrations are intended to takeplace in two planes at right angles to one another, and in consequencethe vibration shafts I1 and I8 are disposed with their axes at rightangles to one another.

Sub-frame 3|, which is mounted by the bearings described on shaft I1, isguided for its vertical movements by means of a plate I3I. This platehas tenons I32 arranged vertically one above the other to engage incorresponding grooves in an end bearing standard I00, and on theopposite face has other tenons I33 in line at right angles to tenonsI32, and these tenons I33 slide in grooves formed to correspond withthem in the wall of sub-frame 3|.

A similar plate I34 is interposed between subframe 3| and table 32, thelatter having grooved uides I35 to engage tenons I36 on plate I34. Thelatter also has other tenons I31 which enage in grooved guides I38 insub-frame 3 I. Thus, it will be clearly seen that the vibratory tablecan move independently of the sub-frame in its guides in one direction,and is bodily moved by the subframe in a direction at right angles, thislatter movement of the sub-frame being permitted and guided by reason ofthe provision of plate I3 I.

The three portions 24, 25 and 26 of the sleeve are interengaged by dogsas shown at 35 and are held thus in engagement with one another afterassembly by means of thrust bearing 36. The outer end of sleeve portion24 where it projects from hearing housing 29, is formed as one elementof a comparatively finely toothed clutch 31 and this oo-operates with asecond companion clutch element 38, splined on the left hand end ofshaft I1. Thus the clutch element 38 may be moved into and out fromengagement with the clutch element 31 in order to lock or free thesleeve 24, 25 and 26 to and from shaft I1 respectively.

When adjusting the amplitude of vibration imparted from shaft I1relative rotation between the shaft and its sleeve will have to be madeand for this adjustment the clutch 31, 38 is actuated by the followingmeans.

Shaft I1 is formed with a screw threaded enlargement 61 and this isengaged by nut 68. In the nut 68 is formed a groove accommodating asplit ring 18 which is housed in a recess formed in gear ring 13. Thesplit ring and gear ring 13 are secured to clutch member 38 by means ofscrews and dowels, holes 12 are drilled in the nut to give access tothese screws and dowels. The gear teeth on gear ring 13 are engageablewhen clutch 31, 38 is disengaged by pinion 14 secured to and rotatablewith shaft 15. The shaft 15 is slidable in bearing 16 and is normallyspring urged outwardly by means of spring 11 compressed between the endof bearing 16 and the interior face of a cap 18 which is screw-threadedon to shaft 15 and is secured thereon by means of a lock nut 19.

A sleeve 84 with clutch teeth machined on one end is secured to shaft 15by means of a pin 89 and is engageable by a similar sleeve 8| withclutch teeth formed thereon. The sleeve 8| is secured to crank handle82.

Thus when the clutch 31, 38 has been disengaged as shown in Figure 2,crank handle 82 can be applied to shaft 15 and the whole moved inwardlyagainst spring 19 until pinion 14 meshes with gear ring 13. Rotation ofcrank handle 12 will then rotate shaft I1 because clutch member 38 issplined as at 83 to shaft I1.

After the shaft has been adjusted to its required angular position crankhandle 82 is removed, spring 11 moves shaft 15 to withdraw pinion 14from engagement with gear ring 13 and thereafter by turning nut 68 theclutch part 38 will be moved back into engagement with clutch part 31.As nut 68 can rotate freely with respect to ring 10, the clutch part 38will not be rotated when nut 68 is rotated, and rotational movement ofthe latter, by engagement with thread 61 will, according to direction ofrotation, move the clutch member in one direction or the other. Theouter surface of nut 68 is formed to be readily engageable by a tool bywhich it can be rotated when desired.

One of the clutch elements 31, 38 is marked on the outside with a scaleto which a setting mark on the companion element can be adjusted inorder to regulate and ascertain the angular movement of the sleeverelatively to the shaft for the purpose of adjusting the throw whichwill be imparted vertically to the sub-frame 3| as shaft I1 is rotated.Thus adjustment is, of course, obtained by altering the angularrelationship of the eccentric portions of the shaft and sleeve.

A second and similar vibratory shaft I8 (Figure 3) and similar adjustingdevices therefor are provided. As in the main, the shaft I8 and itssleeve 44 will be similar to the shaft I1 and its sleeve, no detaileddescription of this second vibratory shaft construction is thought to benecessary but it should be stated that in this case the two clutchelements corresponding to 31, and 38 are indicated at 48 and 4|. Locknuts 42 and 43 are provided to hold the clutch parts 46 and 4| inengagement after they have been sent relatively to one another toproduce the relative angular adjustment required between the eccentricportions of shaft I8 and its surrounding eccentric sleeve 44.

After clutch parts 48 and 4| have been separated a tool I40 can beapplied to clutch part 4| in order to turn shaft I8 within its sleeve ina similar manner to and for the same purpose as that for which shaft I1is angularly adjustable relatively to its sleeve after clutch 31, 38 hasbeen disconnected.

Sleeve 44 is received in anti-friction bearing 45 carried by table 32 sothat horizontal vibrations are imparted directly to the table. Thus thelatter can be subjected to vertical vibrations from shaft I1 andhorizontal vibrations fromshaft I8 and the amplitude of the vibrationsderived from the rotation of both these shafts is capable of adjustmentin very fine degrees from zero to whatever maximum is imposed by thedegree of an eccentricity of the shafts and sleeves.

When it is necessary to adjust the phase angle of the vibrationsimparted to table 32 from vibratory shafts I1 and I8, it is necessary torotate one or the other or both of these shafts in company with itssleeve without disturbing the angular adjustment between that shaft andits sleeve. For this purpose it is necessary first to free the maindriving bevel gear I4 from driving engagement with bevel gears I5 andI6.

In order to enable this disconnection to be effected the driving shaftis in two parts I3 and H3. One part I3 is mounted in bearings II and I2and the other, H3 is mounted in bearings 41 carried in housing 48 whichis itself carried in a bracket 49 at the base of sub-frame 3|, so as tobe movable axially.

The driving power is transmitted from the driving shaft I3 to the other3 by means of a universal coupling 85, one half of which is secured bysplines to I 3. The other half I I3 is splined to the coupling but notsecured, allowing driving shaft 3 to be axially movable therein whenmoving the housing 48 which carries the shaft H3 and the bevel gear I4which is splined to it, into the disengaged position.

The main bevel gear I4 is disengaged by means of a hand wheel 55 securedby a pin to a screw 53. The screw is mounted in a bearing 54 secured tothe side of sub-frame 3|, any unintentional axial movement of screw 53being eliminated by adjusting two locknuts 58. As the handwheel 55 andscrew 53 rotate in one direction, the screw operates the rack 52 whichis carried in a guide 5| formed in the top of the bracket 49. The rackmeshes with the teeth 56 formed onv the housing 48 and rotates thehousing. This SEARCH rotational movement is converted into an axialmovement by co-operation of the helical slot 56, formed in housing 48,and an actuating pin 51. This actuating pin is secured by means of athread and pin 81 to the base of bracket 49. Thus shaft H3 is movedendwise so as to carry the main bevel gear l4 out of engagement withpinions I5 and I6 when it is desired to adjust the phase angle.

The main bevel gear [4 is engaged by rotating the handwheel 55 in theopposite direction to that described for disengagement so operating thescrew 53 and rack 52 and rotating the housing 48 which moves axially,owing to the helical slot 56 and the actuating pin, back to engagedposition. When engaged position is reached the housing is held by therack, which stops rotary movement and is locked between the actuatingpin and the locking plate 86; this stops axial movement. The lockingplate 86 is secured to the back of the housing 48 by means of screws.Thus shaft H3, is moved back to engaged position carrying main bevelgear M to its original position meshing with pinions l5 and Hi.

The main drive can be obtained by any preferred prime mover, such as anelectric motor 60, as shown in Figure 1. As it is difiicult commerciallyto obtain a motor which can be run at any speed from zero to the highspeeds required, it is preferable to employ a motor having a slowermaximum speed than that requisite for the maximum vibration speed and togear this motor by a 2:1 step-up gear or a step-up gear of any otherpreferred ratio as may be found necessary. The motor shaft 6|, as willbe seen in Figure 3, is thus geared by step-up gearing 62 to shaft l3.

In the case of certain aircraft instruments it is sometimes necessarythat the internal mechanism thereof should be rotated during thevibration test. For this purpose a flexible drive is provided, indicatedin Figure 1 at 63 and this flexible shaft is driven by a comparativelysmall motor (not shown) housed within the base portion of the apparatus.For the sake of illustration, flexible shaft 63 is shown as connected tothe driving spindle to one or more of the instruments in an instrumentpanel 64 shown in the position in which it will be carried betweenbrackets 65 supported on the main table 32. Flexible shaft 63 willpreferably be provided at 66 with a nipple or other connector by whichit can be readily attached to and detached from the instrument spindle.

It will be understood from the foregoing description that the vibratorytable can be subjected simultaneously to vibrations in two differentplanes and that the eccentric portions of the vibratory shafts inrelation to the eccentric sleeves surrounding them can be adjusted toproduce vibrations ranging from zero to the desired maximum. Hencevibrations of any magnitude from zero to this maximum can be applied totable 32 in either plane singly or in both planes simultaneously andmoreover the phase angle of the two sets of vibrations can be readilyand rapidly changed as and when desired in addition to changing theamplitude thereof.

I claim:

1. A vibration test machine comprising in combination a vibratory table,a carriage for the table permitting movement of the latter in two planesangularly displaced, at least two rotary shafts, each having aneccentric coupling to the table, with the two shafts disposed with theiraxes angularly displaced with respect to one another at the requiredangle, and means to adjust the eccentricity of the coupling between eachshaft and the table.

2. A vibration test machine according to claim 1 in which the operativeportion of each vibration shaft is formed, as to its outer surface,eccentrically with respect to the axis of rotation of the shaft.

3. A vibration test machine according to claim 1 in which part of theeccgM En g Q Q N-..

each vibration shaft and the table comprises a sleeve which surroundsthe shaft and which has its operative surface formed eccentrically withrespect to its through-way axis.

4. A vibration test machine according to claim 1 in which part of theqssn isicsgslinebsinge each vibration shaft and the table comprises asleeve which surrounds the shaft and which has its operative surfaceformed eccentrically with respect to its through-way axis, and in whicheach vibration shaft is coupled to its associated sleeve by means ofadisconnectable coupling.

5. A vibration test machine according to claim 1 comprising a maindriving shaft, a main driving gear rotated thereby, other gears whichmesh with the main driving gear and are coupled respectively to thevibration shafts, and means to connect and disconnect at will the maindriving gear from the two driven gears.

6. A vibration test machine according to claim 1 comprising a maindriving shaft, a main driving gear rotated thereby, other gears whichmesh with the main driving gear and are coupled respectively to thevibration shafts and means to connect and disconnect at will the maindriving gear from the two driven gears, said means comprising a bearingcarrying the main driving gear, means for rotatably mounting the bearingin a support, means to rotate the bearing, and a cam device operable onthe bearing as it is rotated for moving it axially.

7. A vibration test machine according to claim 1 comprising a maindriving shaft, a main driving gear rotated thereby, other gears whichmesh with the main driving gear and are coupled respectively to thevibration shafts, means to connect and disconnect at Will the maindriving gear from the two driven gears, said means comprising a bearingcarrying the main driving gear, means for rotatably mounting the bearingin a support, means to rotate the bearing, and a cam device operable onthe bearing as it is rotated for moving it axially, the said means forrotating the bearing comprising a tangentially disposed rack meshingwith gear teeth formed on the outer surface of the bearing, andoperating means to move the rack endwise to rotate the sleeve.

8. A vibration test machine according to claim 1 comprising a maindriving shaft, a main driving gear rotated thereby, other gears whichmesh with the main driving gear and are coupled respectively to thevibration shafts, means to connect and disconnect at will the maindriving gear from the two driven gears, said means comprising a bearingcarrying the main driving gear, means for rotatably mounting the bearingin a support, means to rotate the bearing, and a cam device operable onthe bearing as it is rotated for moving it axially, the said means forrotating the bearing comprising a tangentially disposed rack meshingwith gear teeth formed on the outer surface of the bearing, andoperating means which serves to move the rack endwise and comprises alead screw engaging the rack and rotatable in fixed hearings in themachine.

9. A vibration test machine according to claim 1 comprising a maindriving shaft, a main driving gear rotated thereby, other gears whichmesh with the maindriving gear and are coupled respectively to thevibration shafts and means to connect and disconnect at will the maindriving gear from the two driven gears, said means comprising a bearingcarrying the main driving gear, means for rotatably mounting the bearingin a support, means to rotate the bearing, and a cam device operable onthe bearing as it is rotated for moving it axially, the said cam meanscomprising a slot and a pin working therein whereof the slot and pin areprovided one on the bearing and one on a fixed guide in which thebearing is axially movable.

10. A vibration test machine according to claim 1 in which theoperative, portion of the sleeve 20 surrounding one of the vibrationshafts is received within a bearing in the table itself, and the latteris mounted on a sub-frame over which itcan move under vibrationsimparted by the shaftjust referred to, and the operative portion of thesleeve of the other vibration shaft is received in a bearing carried bythe sub-frame.

11. A vibration test machine according to claim 1 in which an auxiliarymotor is housed within the .machine and a flexible driving shaftconnected with the motor is provided for attachment to a rotating partof an instrument to be tested for vibration by the machine.

CYRIL' MAURICE GRAHAME CALVER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,774,769 Spear July 19, 19271,901,122 Robins Mar. 14, 1932 2,227,499 Allendorf Jan. 14, 19412,349,778 Teplow May 23, 1944

